1. Documentation
×

CCO-based workflow for OLM-managed Operators with Azure AD Workload Identity

When an OKD cluster running on Azure is in Workload Identity / Federated Identity mode, it means the cluster is utilizing features of Azure and OKD to apply user-assigned managed identities or app registrations in Microsoft Entra ID at an application level.

The Cloud Credential Operator (CCO) is a cluster Operator installed by default in OKD clusters running on cloud providers. Starting in OKD 4.14.8, the CCO supports workflows for OLM-managed Operators with Azure AD Workload Identity.

For the purposes of Azure AD Workload Identity, the CCO provides the following functions:

  • Detects when it is running on an Azure AD Workload Identity-enabled cluster

  • Checks for the presence of fields in the CredentialsRequest object that provide the required information for granting Operators access to Azure resources

The CCO can semi-automate this process through an expanded use of CredentialsRequest objects, which can request the creation of Secrets that contain the information required for Azure AD Workload Identity workflows.

Subscriptions with automatic update approvals are not recommended because there might be permission changes to make prior to updating. Subscriptions with manual update approvals ensure that administrators have the opportunity to verify the permissions of the later version and take any necessary steps prior to update.

As an Operator author preparing an Operator for use alongside the updated CCO in OKD 4.14 and later, you should instruct users and add code to handle the divergence from earlier CCO versions, in addition to handling Azure AD Workload Identity token authentication (if your Operator is not already enabled). The recommended method is to provide a CredentialsRequest object with correctly filled Azure AD Workload Identity-related fields and let the CCO create the Secret object for you.

If you plan to support OKD clusters earlier than version 4.14, consider providing users with instructions on how to manually create a secret with the Azure AD Workload Identity-enabling information by using the CCO utility (ccoctl). Earlier CCO versions are unaware of Azure AD Workload Identity mode on the cluster and cannot create secrets for you.

Your code should check for secrets that never appear and warn users to follow the fallback instructions you have provided.

Authentication with Azure AD Workload Identity requires the following information:

  • azure_client_id

  • azure_tenant_id

  • azure_region

  • azure_subscription_id

  • azure_federated_token_file

The Install Operator page in the web console allows cluster administrators to provide this information at installation time. This information is then propagated to the Subscription object as environment variables on the Operator pod.

Additional resources

Enabling Operators to support CCO-based workflows with Azure AD Workload Identity

As an Operator author designing your project to run on Operator Lifecycle Manager (OLM), you can enable your Operator to authenticate against Azure AD Workload Identity-enabled OKD clusters by customizing your project to support the Cloud Credential Operator (CCO).

With this method, the Operator is responsible for creating the CredentialsRequest object, which means the Operator requires RBAC permission to create these objects. Then, the Operator must be able to read the resulting Secret object.

By default, pods related to the Operator deployment mount a serviceAccountToken volume so that the service account token can be referenced in the resulting Secret object.
Prerequisities

  • OKD 4.14 or later

  • Cluster in Azure AD Workload Identity mode

  • OLM-based Operator project

Procedure

  1. Update your Operator project’s ClusterServiceVersion (CSV) object:

    1. Ensure your Operator has RBAC permission to create CredentialsRequests objects:

      Example clusterPermissions list 
      # ...
install:
  spec:
    clusterPermissions:
    - rules:
      - apiGroups:
        - "cloudcredential.openshift.io"
        resources:
        - credentialsrequests
        verbs:
        - create
        - delete
        - get
        - list
        - patch
        - update
        - watch

    2. Add the following annotation to claim support for this method of CCO-based workflow with Azure AD Workload Identity:

      # ...
metadata:
 annotations:
   features.operators.openshift.io/token-auth-azure: "true"

  2. Update your Operator project code:

    1. Get the client ID, tenant ID, and subscription ID from the environment variables set on the pod by the Subscription object. For example:

      // Get ENV var
clientID := os.Getenv("CLIENTID")
tenantID := os.Getenv("TENANTID")
subscriptionID := os.Getenv("SUBSCRIPTIONID")
azureFederatedTokenFile := "/var/run/secrets/openshift/serviceaccount/token"

    2. Ensure you have a CredentialsRequest object ready to be patched and applied.

      Adding a CredentialsRequest object to the Operator bundle is not currently supported.

    3. Add the Azure credentials information and web identity token path to the credentials request and apply it during Operator initialization:

      Example applying CredentialsRequest object during Operator initialization 
      // apply credentialsRequest on install
credReqTemplate.Spec.AzureProviderSpec.AzureClientID = clientID
credReqTemplate.Spec.AzureProviderSpec.AzureTenantID = tenantID
credReqTemplate.Spec.AzureProviderSpec.AzureRegion = "centralus"
credReqTemplate.Spec.AzureProviderSpec.AzureSubscriptionID = subscriptionID
credReqTemplate.CloudTokenPath = azureFederatedTokenFile

c := mgr.GetClient()
if err := c.Create(context.TODO(), credReq); err != nil {
    if !errors.IsAlreadyExists(err) {
        setupLog.Error(err, "unable to create CredRequest")
        os.Exit(1)
    }
}

    4. Ensure your Operator can wait for a Secret object to show up from the CCO, as shown in the following example, which is called along with the other items you are reconciling in your Operator:

      Example wait for Secret object 
      // WaitForSecret is a function that takes a Kubernetes client, a namespace, and a v1 "k8s.io/api/core/v1" name as arguments
// It waits until the secret object with the given name exists in the given namespace
// It returns the secret object or an error if the timeout is exceeded
func WaitForSecret(client kubernetes.Interface, namespace, name string) (*v1.Secret, error) {
  // set a timeout of 10 minutes
  timeout := time.After(10 * time.Minute) (1)

  // set a polling interval of 10 seconds
  ticker := time.NewTicker(10 * time.Second)

  // loop until the timeout or the secret is found
  for {
     select {
     case <-timeout:
        // timeout is exceeded, return an error
        return nil, fmt.Errorf("timed out waiting for secret %s in namespace %s", name, namespace)
           // add to this error with a pointer to instructions for following a manual path to a Secret that will work on STS
     case <-ticker.C:
        // polling interval is reached, try to get the secret
        secret, err := client.CoreV1().Secrets(namespace).Get(context.Background(), name, metav1.GetOptions{})
        if err != nil {
           if errors.IsNotFound(err) {
              // secret does not exist yet, continue waiting
              continue
           } else {
              // some other error occurred, return it
              return nil, err
           }
        } else {
           // secret is found, return it
           return secret, nil
        }
     }
  }
}
      1 The timeout value is based on an estimate of how fast the CCO might detect an added CredentialsRequest object and generate a Secret object. You might consider lowering the time or creating custom feedback for cluster administrators that could be wondering why the Operator is not yet accessing the cloud resources.

    5. Read the secret created by the CCO from the CredentialsRequest object to authenticate with Azure and receive the necessary credentials.